This invention relates to apparatus for converting analog signals to digital signals. More particularly, it is concerned with analog-to-digital converting apparatus employing successive approximation techniques.
Various types of analog-to-digital converting apparatus are well-known and widely used. Many types require circuitry to sample the amplitude of an analog signal and then hold the sample during a conversion process. The conversion process may require that a comparison step be made in succession to determine each bit of the digital output. This type of converter utilizes a single comparator. With such apparatus the total conversion time which is the sum of the delays for each comparison step may be excessive for certain applications. Another type of analog-to-digital converter employs a comparator for each quantum of voltage of the analog signal which is to be converted. The outputs of the comparators are then decoded by decoding logic. Although such a converter operates at very high speed, a large number of comparators and appropriate decoding logic are required.